FYI I found the "valve". On the top of the tank where the pump line come in there is a 90 degree fitting. Remove the fuel line from the fitting, unscrew the fitting from the tank, you don't need to remove the tank. In the fitting there is a ball bearing and a spring, there is a sleeve inside the fitting holding the bearing and spring in. I drilled this sleeve out and removed the bearing and spring, I couldn't find a new fitting the same size. After installing everything back my pump now works fine.